Bioengineers develop new class of human-powered bioelectronics

Date:
September 30, 2021
Source:
University of California - Los Angeles
Summary:
A team of bioengineers has invented a novel soft and flexible self-
powered bioelectronic device. The technology converts human body
motions -- from bending an elbow to subtle movements such as a
pulse on one's wrist -- into electricity that could be used to
power wearable and implantable diagnostic sensors.



FULL STORY ==========================================================================
A team of bioengineers at the UCLA Samueli School of Engineering has
invented a novel soft and flexible self-powered bioelectronic device. The technology converts human body motions -- from bending an elbow to subtle movements such as a pulse on one's wrist -- into electricity that could
be used to power wearable and implantable diagnostic sensors.


==========================================================================
The researchers discovered that the magnetoelastic effect, which is
the change of how much a material is magnetized when tiny magnets are constantly pushed together and pulled apart by mechanical pressure, can
exist in a soft and flexible system -- not just one that is rigid. To
prove their concept, the team used microscopic magnets dispersed in a paper-thin silicone matrix to generate a magnetic field that changes
in strength as the matrix undulated. As the magnetic field's strength
shifts, electricity is generated.

Nature Materialspublished today a research study detailing the discovery,
the theoretical model behind the breakthrough and the demonstration. The research is also highlighted by Nature.

"Our finding opens up a new avenue for practical energy, sensing and therapeutic technologies that are human-body-centric and can be connected
to the Internet of Things," said study leader Jun Chen, an assistant
professor of bioengineering at UCLA Samueli. "What makes this technology
unique is that it allows people to stretch and move with comfort when the device is pressed against human skin, and because it relies on magnetism
rather than electricity, humidity and our own sweat do not compromise its effectiveness." Chen and his team built a small, flexible magnetoelastic generator (about the size of a U.S. quarter) made of a platinum-catalyzed silicone polymer matrix and neodymium-iron-boron nanomagnets. They then
affixed it to a subject's elbow with a soft, stretchy silicone band. The magnetoelastic effect they observed was four times greater than similarly
sized setups with rigid metal alloys. As a result, the device generated electrical currents of 4.27 milliamperes per square centimeter, which
is 10,000 times better than the next best comparable technology.

In fact, the flexible magnetoelastic generator is so sensitive that it
could convert human pulse waves into electrical signals and act as a self-powered, waterproof heart-rate monitor. The electricity generated
can also be used to sustainably power other wearable devices, such as
a sweat sensor or a thermometer.

There have been ongoing efforts to make wearable generators that harvest
energy from human body movements to power sensors and other devices,
but the lack of practicality has hindered such progress. For example,
rigid metal alloys with magnetoelastic effect do not bend sufficiently
to compress against the skin and generate meaningful levels of power
for viable applications.

Other devices that rely on static electricity tend not to generate enough energy. Their performance can also suffer in humid conditions, or when
there is sweat on the skin. Some have tried to encapsulate such devices
in order to keep water out, but that cuts down their effectiveness. The
UCLA team's novel wearable magnetoelastic generators, however, tested
well even after being soaked in artificial perspiration for a week.

A patent on the technology has been filed by the UCLA Technology
Development Group.

========================================================================== Story Source: Materials provided by
University_of_California_-_Los_Angeles. Note: Content may be edited for
style and length.


========================================================================== Journal Reference:
1. Yihao Zhou, Xun Zhao, Jing Xu, Yunsheng Fang, Guorui Chen,
Yang Song,
Song Li, Jun Chen. Giant magnetoelastic effect in soft
systems for bioelectronics. Nature Materials, 2021; DOI:
10.1038/s41563-021-01093-1 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2021/09/210930111059.htm

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